Research on four projects concerns generally the events of oocyte maturation and early post fertilization development in amphibians. When steroid hormones induce oocyte maturation, the initial site of action appears to be the oocyte surface and this is being tested in attempts to induce maturation with steroids covalently attached to insoluble matrices. The possible involvement of adenyl cyclase is being tested by measurements of cyclic AMP levels before and after oocyte exposure to steroids. Attempts also are being made to isolate and identify an intracellular "second factor" which in itself is capable of inducing maturation when injected into oocytes. In the second project rates of RNA synthesis during oocyte maturation are calculated from kinetics of radioactive precursor incorporation into RNA and changes in pool specific activity. Qualitative studies involve sucrose gradient and electrophoretic analysis of total RNA. Third, we are measuring levels of de novo RNA polymerase synthesis at several developmental stages to determine if the "store" of polymerase localized within the germinal vesicle is sufficient for the requiremets of early development. Finally, identification of the cytoplasmic component involved in the formation of primordial germ cells is being pursued. Ultrastructural studies are used to "trace" distinctive electron dense "germinal material" throughout oogenesis and early development. Autoradiography is used to determine if this material incorporates radioactive precursors administered at various stages of oogenesis. Cell fractionation procedures are being tested in attempts to isolate the electron dense bodies directly. Fractions are injected into the vegetal hemisphere of UV irradiated eggs to determine biological activity in promoting germ cell formation.